Twist-drill grinder.



HQ M. Bumm. TWIST DRILL GRINDER.Y APPLIOATOH FILED MAY 10, 1913. Lmgg, menta@ A101114, i914 2 SHEETS-SHEET 1.

i refranes.

HOWARD M. BOGART, F CINCINNATI, OHIO.

Specification of Letters Patent.

TWIST-DRILL GRINDER.

Patented Apr. 14, 1 91.4.

` Application filed May 10, 1913. Serial No. 766,810.

. ot which the following is a specification.

My invention relates to improvements in mechanism to grind twist drills.

,One ot' its objects is to provide improved mechanism to hold drills of various diameter .inposition to be ground upon the periphery ot' the wheel.

Ai-iother object is to provide improved means to hold and adjust the drills to posl- Another object is to provide an improvement in the position and direction of oseillatioii of the drills.

Another object is to provide improved means to support and adjust the drill supporting members relative to the grinding wheel standard.

My invention also comprises certain details of form, combina-tion and arrangement, all of which will be fully set forth in the description of the accompanying drawings, in which:

Figure 1 is a side elevation of my improved grinder. Fig. 2 is a plan view looking in the direction of the arrow in Fig. 1. Fig. 3 is a detail end view of the drill holder. Fig. 4 is a perspective view of the adj listing block detached. Figs. 5 and 6 are detail diagrams illustrating'the relative positions of large and small drills. Fig. 7 is a sectio-nal detail on line o fo of Fig. 2. Fig. 3 is a sectional detail on line z e of Fig. 2. Fig. 9 is a sectional detail on line a: of Fig. 2. Fig. 10 is an enlarged diagram of the cutting end o'l'.' a drill.A Fig. 11 'is a diagram illustrating the lnanner in which the grinding operation is` effected. Fig. 12 represents a serios of sections across the drill lip Fig. 1() on the lines 40, 41, an'd 42 respectively.

ln the accompanying drawings, A represents' a standard or. frame in which the spindle 2 of theI grinding wheel B is jourualed. A boss or 1 rojection on the standard A is faced and provided with a T-slot'3 and ways 4 parallel to the axis of the'wheel'li. A block 5 is seated and adjust-able by means of a rib 51 iipouV the ways 4 and a slotted bracket 6 is adjustably mounted upon the block 5, and guided relative thereto vby a rib .perforation in the block5 and the slot 9 of bracket 6 and the mit tightened to lock the-parts in position.

At the free end of the bracket (S is a conical journal boX 10 to receive the journal 11 of the drill holder 121 The drill :holder comprises in addition to its journal 11 an arm 14 projecting out so as to nearly intersect the axis of oscillation of the journal 11, a plane drill supporting face f having a side guide 7c at substantially right angles to the drill supporting face, and a rearwardly projecting rod 15 carrying adjustable supporting members 1G and 17 to support the rear end of the drill laterally and endwise. The rod 15 is splined or grooved on its under side and the laterally supporting membel 16 has a spring actuated key m engaging the key yway of rod 15 to frietionally hold the lateral support in adjusted position thereon. Said lateral support has a plane drill supporting face 18 and a side guide 19in line with the drill supportingV faces f and f. The supporting member 1 7 comprises' a base (l splined to the rod 15. A

A rod 20 is mounted parallel to rod 15 in a recess in member d and has a key seat 21 and a. key 22 to hold it against rotation. The member (l is split opposite rod 15 and also opposite rod 20, vand a bolt 24 and nut-25 enable member d to be simultaneously locked to or released from rods 15 and 20. The forwargl end of vrod 20 is counterbored and the sh. nk 26 of the end thrust support N is seated therein and provided with a pin 27 seating in the key seat slot of rod 20. The

.end of' rod 20 and the enlarged portion of shank 2G are threaded right and left handedly respectively, and a sleeve I) engaging said threads provides a tine adjustment for the thrust support N.

At the right of the journal 11 is provided a rectangular vseat 30 to which is litted a (-.ounterweight 31 which serves to practically counterbalance the weight of the drill holder members in their various positions of oscil lation. Said member 31 also carries a lug ,32 which engages an ear 33 on the bracket 6 to limit the oscillating movement of the drill holder in a downward direction. The journal l1 is locked iu' the box 10 and the lOFi greater amount of radi'us is given to theV drill lip while the position of the drill axis above the axis of oscillation determines the amount of clearance given to the drill lips, which is also made dependent upon the diameter and position ot the drill.

In practice the drills are not locked to the drill holder during the grinding operation, but are laid upon the supporting faces and the end thrust adjustments made, and then the operator grasps the drill and rod 15 between the members 12 and 16 with one hand to hold the drill in place and oscillates the holder with the other hand. This permits the drills to be very quickly placed and shifted to present the opposite lip.

The bracket 6 is preferably mounted so as to bring its journal 10 to the rightl hand ot' the wheel B- and so t-liat the axis of ,oscillation will intersect or nearly intersect the periphery of Vthe wheel at an acute angle and so that the limits of oscillatory movement with the drill in contact with the wheel will extend from a substantially horizontal positionat one ext-renie through approximately 120 degrees to a position of downward inclination of the drill support. Ihe relation of the drill holder and Wheel are such that when the drill holder moving upwardly passes a. horizontal position, the

' drill passes out of Contact with the wheel,

and thus avoids liability of injury to the forward edge of the opposite lip. This position of the drill holder is most convenient tor the operator to hold Vand oscillate the holder and observe the effect produced. It also provides for a tendency of the drill to rest. by gravity against the end thrust plate instead of. working toward the wheel.

The oscillation of the drill holder with reference to the periphery of the wheel as herein illustrated provides for grinding the` drilllips to a new outline. Fig. 11 indicates a cone rotatable on the axis lw fw, and

its face would indicate the path traveled by the drill lips due to the oscillat-ion of the drill holder. Theperiphery of the wheel being circular would only contact with the face of the cone along a line. across `the face ot the wheel. Such a line of Contact coincident with a radial line ofthe face of the cone. is represented by t t, and s the surface ground by such a contact, while r 1* represents a line of contact which is diagonal to one of the radial lines of the face of the cone, and s a face ground by such contact. vIn practice lthe line of contact shifts progressively from that indicated at t t to that indicated at 1' 1' as the grinding of thel drill lip progresses, commencing at the cutting edge of the drill lip '10, which is a straight line and a fraction of a true cone to the line'41 where the drill lip tace is ground slightly concave, and thenceto the line 42 where the face of the-drill lip is still more concave. The'result of this is that the drill has greater clearance and the point or center line 43 where a scraping action occurs in drilling is sharper and better able to penetrate the work.

In practice the drill holder is adjusted so that Wit-h drills of small diameter the cutting edge of t-he drill will contact with the wheel at the commencement of the grinding operation substantially at thepoint where a line y g/ Fig. 1 intersects the periphery ot the wheel, said line y y'intersecting the axis ot the wheel and being parallel with the adjusting faces of members 5 and lVith -drills of larger diameter contact occurs higher up on the wheel.

lVhere drills or reamers with three or more lips are to be ground the plate or block 5 and bracket G are adjusted toward the left until the major portion of the lips, all except the one to be ground are to the left of the periphery of the wheel, and not in posit-ion to contact with the wheel when the drill holder is oscillated. The adjustment ot' the members 5 and 6 also providestor securing the proper'relatioii of the drill holder and its axis of oscillation with wheels of different diameter, or to compensate for wear of the wheel. By present-ing the drills to theperiphery ofthe wheel the lineot contact is very narrow and hence there is very little tendency to iiijuriously heat the drills, and ample clearance for the escapey of the cuttings.

The mechanism herein illustrated and described is capable of considerable modification without departingffrom the principle of my invent-ion.

Having described my invention, what I claim is:

v1. A twist drill grinder comprising a grinding wheel, a bracket supported relative to said wheel and adjustable parallel to and transversely to the axis of said wheel and provided with a journal to support the drill holder, a drill holder jonrn'aled to said bracket so as to oscillate `from below to a horizontal position to present drills to the periphery of the wheel, and a counterweight to substantially counterbalance the weight of said drill holder.

2. ln a twist drill grinder in combination lwith a grinding wheel and a supporting bracket a drill holder comprising a member journaled to said bracket so as to oscillate relative thereto, said. member being provided with a face to support the drills, a drill lip p. gage, a side guide for thedrills, and a rearto said bracket so as to wheel, j said Wheel, said drill holder comprlsing a drillA supportmg wardly projecting shank, a lateral guide for the rear end of the drills splined to and adsv justable upon said shank, a thrust guard holder sp-lined toandadjustable upon said 10 shank,

a thrust guard splined to said holder, and means to adjust said thrust guard relative tosaid holder.-

3. lA -twist drill grinder comprising a standard, a grinding wheel rotatablyT sup- 15 ported upon said standard, a block adjustable upon said standard parallel to the axis 'of the grinding wheel a bracket carried. by said block and adjustab .axis of` said wheel, .a drill holder journaled be oscillated relative thereto upon an axis adjustable by means of said block and bracket to intersect at an acute angle the to-present drills to the periphery of substantially horizontal face, a Asubstantially vertical side guide, a drill lip guide, vguard to automatically position drills of dif- 30 ferent'diameter.

60 adjustable longitudinally '4.'A twist drill grinding lyvheel, va mounted so 'as to obliquely intersecting the plane of rotation grinder comprising a drill holder pivotally of the grinding wheel slightly outside of the periphery 'of the wheel, said drill holder comprising a substantially horizontal drill supporting face and a substantially vertical side guide,said drill holder` being provided 40 with a drill lip guide at one end and an adjustable end or thrust guard at the opposite end.

- 5. Ay twist drill grinder comprising a grinding wheel, a drill holder to present the drills to the periphery of saidA wheel pivot'- allymounted upon an adjustable axis soas to oscillate below the `center of said wheel upon an axis obliquely intersecting the plane of rotation of said wheel outside the periphery of said Wheel, said drill holder comprising a substantially horizontal drill supporting face and a substantially vertical side guide, said drill holder being provided m with a drill lip guide at one end and an ad- `justable end or thrust guard at the opposite end.

6. A twist drill grinder comprising a grinding Wheel, a grindingwheel standard, a bracket mounted upon said standard and and transversely a drill holder to ofthe axis of said wheel,

. present the drills tothe periphery ofsaicl 'foro le transversely to theA periphery of said .grinding and an adjustable thrust` oscillate upon an axis 'thrust rod, and

the axis of oscillation -ward end 0f the drill havmg a lip rest and a rearwardly projecting shank, a lateral rest the rear end of the drill slidably'l and non-rotatably mounted upon said shank and frictionally held to its adjusted position, and an adjustable end or thrust guard slidably and non-rotatably mounted upon the rear end of said shank.

8. In a twist drill grinder an oscillating drill holder having lateral drill supports and a lip rest, and an end or thrust uard-comprising a slotted clamping mem er having a recess to slidably and non-rotatively engage a supporting shank a recess to slidably and non-rotatably support a thrust rod, a

bolt seated in a recess in said clamping member and transversely to said slots to simultaneously clamp sai clamping melnber to its supporting shank and to clamp said thrust rod to said vclampin member.

9. In a twist drill grin er anvoscillating drill holder having means to support a drill laterally and an end or thrust uard comprising va slotted clamping-mem er having a recess to slidably and non-'rotatably ena supporting shank, a .recess to slidably gae an non-rotatably support a. thrust rod, a

guard member adjustably mounted upon said means to simultaneously clamp said clamping member to its support and said thrustrod to said clamping member.

10. In a twist drill grinder a grinding wheel, an oscillating drill holder to support a-drill in contact with said wheel and comprising a substantially horizontal drill supporting face, a substantially vertical drill side guide and a drill lip rest, all forming a junction at a common pointlocated upon of said drill holder,

to automatically position drills of different In testimonyiwhereof I have atlxed my signature in presence of two witnesses.

Y HOWARD M. BDGART. Witnesses:

E. W. MCCALLISTER, C. W. MILES. 

